Protocols And Experiments Of Quantum Cryptography

Since its formal establishment at the beginning of the 20th century,quantum me-chanics has profoundly affected the development of science and technology and pro-moted the progress of human society.In 1985,Deutsch developed a quantum algorithm using quantum coherence to show that quantum computing is superior to classical com-puting in efficiency.Subsequently,the quantum algorithm proposed by Shor exponen-tially increases the speed of the factor decomposition of large numbers,thus threatening the security of our current classical cryptosystems(such as RSA,DES,and AES,etc.)based on the computational complexity of complex mathematical problems.Quantum cryptography(Quantum Key Distribution)represented by quantum cryptography came into being.Its security is based on the basic principle of quantum mechanics,combined with a one-time encryption method,quantum key distribution can ensure absolute se-cure communication in the sense of information theory.Since Bennett and Brassard proposed the BB84 protocol in 1984,quantum key distribution has become the most practical research direction in the field of quantum information.In addition to key distribution in cryptography,there are other tasks that are more complex and have practical application value.For example,digital signatures,authen-tication,etc.The classic cryptographic protocols corresponding to these cryptographic tasks also face the threat of quantum computing.Based on quantum mechanics,corre-sponding quantum cryptographic protocols can also be constructed.The concept of the quantum cryptography protocol is more extensive and it includes but is not limited to quantum key distribution protocols,for example,quantum digital signatures,quantum authentication protocols,etc.These quantum protocols are also based on the fundamen-tal principles of quantum mechanics and can also solve the problem of the complete insecurity of classical cryptographic protocols after the appearance of quantum com-puting.Among them,the quantum digital signature protocol can be based on quantum key distribution,and the process of key distribution is exactly the same as quantum key distribution.Therefore,the quantum digital signature protocol is expected to become the next practical quantum cryptographic protocol.Today,identity authentication has important applications in many fields.Quantum identity authentication can guarantee the uniqueness of the identity certificate based on the unclonable law of quantum me-chanics.The uniqueness of the certificate is a unique property provided by quantum mechanics that cannot be achieved by classical methods.Referring to the quantum key distribution protocol,quantum random number is another important research field provided by quantum information.In theory,the quan-tum key distribution protocol is a scheme for generating random numbers remotely,and quantum random number generators only require random number generation lo-cally.The randomness of quantum random numbers comes from the measurement col-lapse hypothesis in quantum mechanics,which can be considered as true randomness.Some quantum random number protocols can generate highly secure random numbers with minimal assumptions about experimental equipment.In terms of generation rate,specific quantum random number generation schemes can also be compared with clas-sical random number generators.Quantum random numbers can provide high-quality,high-rate,and truly secure random numbers for gaming,secure communications,and numerical simulation,etc.The quantum cryptography protocols and quantum random number protocols men-tioned above all provide solutions and important help for information security in the era of quantum computing.The study of quantum cryptography protocols not only ensures information security,but also helps deepen the understanding and research of quantum mechanics.This article focuses on the topic of quantum cryptography and summarizes my research results in quantum cryptography protocols and quantum random numbers,including the following:1.Semi-device-independent quantum random number generator experiment.The practical quantum random number generator often requires the device to be completely trusted by the user,which is often difficult to achieve in practical applications.The semi-device-independent quantum random number generation protocol can generate true random numbers with several simple assumptions towards the experimental device.Based on the scheme of Yun-Guang Han et al.,we have implemented a semi-device-independent quantum random number generation device.Experiments have verified that this device generates high-efficiency true random numbers in the case of high noise and high loss.Compared to previous solutions,the generation efficiency has doubled.2.Three-party semi-device-independent quantum random number generator ex-periment.In the previous quantum random number generation apparatus,there are only preparation side and measurement side.Based on the weak measurement technology,we raised participants of the random number generator to three parties.This experi-ment provides a solution for generating random numbers in a network environment.As a random number generating resource,it may have important applications in fields such as quantum cryptography.3.Practical Quantum Digital Signature Experiment Based on GHz BB84 Quantum Key Distribution System.Based on the phase-encoding Faraday-Sagnac-Michelson in-terferometer quantum key distribution system,a practical quantum digital signature ex-periment was performed.The experimental device has a repetition rate of gigahertz.Compared with previous quantum digital signature experiments,the device provides a relatively balanced solution between practical security,high signature rate,and system robustness.4.Quantum identity authentication protocol based on EPR-steering.EPR-steering is the basic nature of quantum mechanics.We use the unique asymmetry of EPR-steering to construct an authentication protocol by distributing entangled particles to the users.Compared with the previous protocol,this protocol does not require completely error-free and lossless channels.Because of the monogamy of quantum steering,the identity certificate in the protocol are unique,thus improving the security of the entire system.